Driver devices that generate appropriate currents through light sources such as LEDs and laser diodes are known in the industry. For example, a laser diode driver chip can be used to vary the current propagating through a laser diode in order to modulate the light produced by the laser diode. Driver devices are typically available in two distinct circuit flavors—a single ended driver circuit and a differential driver circuit.
The decision whether to use a single ended driver circuit or a differential driver circuit depends on a variety of factors. For example, in some cases, a single ended driver circuit may be selected so as to keep the driver circuitry simple and also to minimize power consumption. However, some pulse signals that are used in the single ended driver circuit for modulating a light source can have sharp rising and falling edges that constitute transient voltage spikes. Such transient voltage spikes can generate an undesirably high level of electromagnetic interference (EMI).
In addition to the EMI issue, a single ended driver circuit can also suffer from other shortcomings that prevent it from being used beyond certain frequency limits. Such shortcomings can include for example, signal distortion and operational instability (oscillations, resonant conditions, etc.) when the single ended driver circuit is operated at high frequencies.
The EMI problem associated with the single ended driver circuit can be mitigated to some extent by using a differential driver circuit wherein pulses of opposing polarities can be used to cancel out transient voltage spikes and minimize the generation of undesirable EMI. However, while such EMI suppression is desirable, the trade-off associated with using the differential driver circuit includes more circuit complexity and higher power consumption. The circuit complexity can arise as a result of having to address signal distortion and operational instability issues when operating the differential driver circuit at high frequencies.
It is therefore desirable to provide a device that offers flexibility in using either a single ended driver circuit or a differential driver circuit while also addressing at least some of the traditional EMI and circuit instability issues.